孤立毫秒脉冲星（IMSP）的起源是天文学中的未解之谜。三星系统动力学质量转移、'被破坏的再循环脉冲星'、起源于中子星的相对论星风蒸发伴星及中子星与大质量白矮星的并合都可能形成IMSP。然而，研究表明前两种形成通道对整个IMSP星族的贡献非常小，而第三种形成通道所需的时标大于Hubble时间。本项目将分析IMSP的相关观测数据，讨论中子星与大质量白矮星并合发生暗的I型超新星（类似SN 2005E）爆发和无超新星爆发伴随的长伽玛射线暴（类似GRB 060614）而形成IMSP的观测证据。最重要的是，本项目分析了现有X-射线和射电毫秒脉冲双星的相关观测数据（见正文图2），发现IMSP也很可能起源于超紧X-射线毫秒脉冲星。这些系统的中子星伴星有着极低质量（大约0.01太阳质量）。本项目将研究这些极低质量恒星长期在X-射线照射下发生动力学质量转移，从而形成IMSP的可能性。

The origin of isolated millisecond pulsars (IMSPs) is still open problem. It is possible to form an IMSPs by dynamical mass transfer in triple stars, 'disrupted recycled pulsar', relative wind from neutron star evaporating its companion, and the merger of neutron star and massive white dwarf. However, the contribution of the first two channels to the total IMSPs' population is too small, and the timescale used in the third channel is longer than the Hubble time. We analyze the observed data of subluminous type I supernova (such as SN 2005E) or long Gamma-ray bursts without accompanying supernova (such as GRB 060614), and find out the samples which are related to the merger in the forth channel. According to the observational data of IMSPs, we investigate the possibility of the merger forming IMSP. The most importantly, by analyzing the data of X-ray MSPs and binary radio MSPs (See Fig. 2), we consider that IMSPs likely originate from ultra-compact X-ray MSPs. In these binaries, the companions of MSPs have extremely low mass (about 0.01 solar mass). These extremely low mass stars have been irradiated by X-ray from accreting neutron stars for billion years. Their temperature and degeneracy change so that their radii increase, which may result in dynamical mass transfer and form IMSPs.